Burkholderia pseudomallei

(endorsed 2001)

Guideline

No guideline value has been established for Burkholderia pseudomallei in drinking water.

General description

Burkholderia pseudomallei, which causes the disease melioidosis, is a motile Gram-negative bacillus commonly found in soil and muddy water in tropical regions. B. pseudomallei can survive in water for prolonged periods in the absence of nutrients, and is acid tolerant (Wuthiekanun et al. 1995).

Melioidosis is most common in northern Australia and South-East Asia. Infection usually results from contact with soil or surface-accumulated water (muddy water). Exposure to environmental B. pseudomallei after heavy rainfall presents the greatest risk. Most infection appears to be through skin cuts or abrasions; however, infection may also occur via other routes, particularly through inhalation or ingestion. The relative importance of these routes of infection is not known.

Australian significance

Melioidosis is an endemic disease in northern Australia and although generally a tropical illness it has been detected in the southwest of Western Australia (Golledge et al. 1992). The first human case was diagnosed in Australia in 1950. Melioidosis is reported with increasing frequency in the Top End of the Northern Territory and B. pseudomallei is the most common organism isolated in fatal community acquired pneumonia. Cases appear throughout the year but peak during the rainy season (Currie 2000).

Two outbreaks of melioidosis have been reported in Australia: in 1990–91 in the Northern Territory and in 1997 in Western Australia (Inglis et al. 1999). In the latter outbreak, indistinguishable isolates of B. pseudomallei were cultured from cases and the potable water supply (Inglis et al. 1999, 2000).

Management

Standard disinfection procedures should be sufficient to eliminate B. pseudomallei from water supplies.

Method of identification and detection

Selective culture techniques have been described (Brook et al. 1997). Confirmation of identity as traditionally been done by biochemical tests (Inglis et al. 1998) but polymerase chain reaction (PCR) based methods may be more accurate. Genetic typing can be performed by several methods, including ribotyping and pulsed field gel electrophoresis (Haase et al. 1995; Inglis et al. 2000).

Health considerations

Melioidosis is a potentially fatal disease. Pneumonia is the most common presentation. Many patients present with milder forms of pneumonia, which respond well to appropriate antibiotics, but some may present with a severe septicaemic pneumonia. Other symptoms include skin abscesses or ulcers, abscesses in internal organs and unusual neurological illnesses such as brainstem encephalitis and acute paraplegia. Individuals without symptoms or known history of disease may also be positive on serological testing. Late onset disease, including acute septicaemia, can occur months or years after initial exposure.

Although melioidosis can occur in healthy children and adults, it mainly occurs in people whose defences against infection are impaired, due either to an underlying condition (e.g. diabetes, chronic renal or lung disease, or alcoholic liver disease), or to poor general health associated with poor nutrition or living conditions.

Derivation of guideline

No guideline is proposed for B. pseudomallei because there is limited evidence for the involvement of drinking water in its transmission in Australia. The numbers of organisms that would be significant for human health are unknown.

If a water supply is implicated as a possible source of melioidosis, investigations should be undertaken to assess whether the supply has been well managed and continually disinfected. The supply should be tested for the presence of the organisms.

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NOTE: Important general information is contained in PART II, Chapter 5

References

Brook MD, Currie B and Desmarchelier PM (1997). Isolation and identification of Burkholderia pseudomallei from soil using selective culture techniques and the polymerase chain reaction. Journal of Applied Microbiology, 82, 589–596.

Currie BJ (2000). The epidemiology of melioidosis in Australia and Papua New Guinea. Acta Tropica, 74, 121–127.

Haase A, Smith-Vaughan H, Melder A, Wood Y, Janmaat A, Gilfedder J, Kemp D and Currie B (1995). Subdivision of Burkholderia pseudomallei ribotypes into multiple types by RAPD analysis provides new insights into its epidemiology. Journal of Clinical Microbiology, 33, 1687–1690.

Inglis TJJ, Garrow SC, Adams C, Henderson M, Mayo M and Currie BJ (1999). Acute melioidosis outbreak in Western Australia. Epidemiology and Infection, 123, 437–443.

Inglis TJJ, Garrow SC, Henderson M, Clair A, Sampson J, O’Reilly L and Cameron B (2000). Outbreak strain of Burkholderia pseudomallei traced to water treatment plant. Emerging Infectious Diseases, 6, 56–59.

Inglis TJJ, Chiang D, Lee GSH and Lim CK (1998). Potential misidentification of Burkholderia pseudomallei by API 20NE. Pathology, 30, 62–64.

Golledge CL, Chin WS, Tribe AE, Condon RJ and Ashdown LR (1992), A case of human melioidosis originating in south west Western Australia. Medical Journal of Australia, 157, 332–334.

Wuthiekanun V, Smith MD and White NJ (1995). Survival of Burkholderia pseudomallei in the absence of nutrients. Transactions of the Royal Society of Tropical Medicine and Hygiene, 89, 491.